There has long been a need for compact yet efficient appliances to be installed within living areas in single and multi-family dwellings as well as in commercial establishments.
Combined water heating systems, i.e., those that provide both potable water and space heating, help to satisfy the need for compact systems for supplying hot water. However, some traditional combined water heating systems may lack protection against the mixing of potable and non-potable water.
Attempts have been made to provide a compact yet efficient combined water heating system that protects potable water from contamination. For example, U.S. Pat. No. 5,485,879 to Lannes discloses a combined water heating system for domestic or commercial use capable of heating water for consumption as well as for space heating. The '879 system comprises a double-wall construction heat exchanger coil (a non-metallic outer wall in contact with a metallic inner wall) incorporated into a standard, glass-lined water heater system. Monofilaments placed between the two walls of the heat exchanger coil provide a path along which potable or non-potable water trapped between walls can travel out of the system. While the '879 system represents a significant improvement over prior systems, continued improvements are sought.
Accordingly, there remains a need for improved heat exchange systems for use in water heater assemblies.